A wheel consists of a wheel rim and a tire. With the tire inflated, the circular inner edge at each side of the tire, which is referred to as bead, is nested inside the rigid outer edges of the wheel rim which are referred to herein as the holding flanges or flanges of the rim. The tire beads and rim flanges are mated to form an air tight seal when the tire is inflated or partially inflated to expand the tire beads outwardly against the rigid flanges.
The problem addressed by the present tool concerns the mounting of tires to wheel rims, e.g., when repairing or replacing a tire and particularly large tires such as mounted on trucks, buses and the like. The tire is positioned or nested between the wheel rim edges and the wheel rim is most often laid on one of its sides. A valve stem provided on the wheel rim enables the installer to connect an air hose and inject air into the cavity formed by the tire and the rim. However, in the deflated condition, the tire bead at the top side of the tire falls away from the rim flange a slight amount creating an air space and air injected through the valve stem simply escapes through that air space. The installer has to figure some way to raise the bead up against the rim flange during the initial injection of air to establish a seal. With some minor amount of air pressure created inside the tire, the seal will be retained as the tire is inflated to the desired pressure.
This problem is particularly burdensome for installing tires on large wheels which can weigh several hundred pounds and are, therefore, difficult for an installer to handle. Two tools are known to be used for addressing this problem. The first is referred to as an air ring and is disclosed in U.S. Pat. No. 3,552,469, issued Jan. 5, 1971. A circular air conduit forming a ring is designed to encircle the wheel-rim just beyond the flange. The ring is connected to an air source and spaced air holes in the ring direct air into the space between the bead and flange. The ring injects air throughout the circumference of the rim to partially inflate the tire and in combination with air also injected through the valve stem, the tire is inflated sufficiently to create the seal.
A second, more recent tool disclosed in U.S. Pat. No. 5,072,764, issued Dec. 17, 1991, includes a portable air tank with a nozzle directly connected to the air tank. The tank and nozzle are designed to inject a predetermined volume of air rapidly through the nozzle. The nozzle outlet end is configured to direct air flow from the nozzle between the bead and rim flange. Whereas the greater portion of the surrounding space between the deflated tire and rim is still exposed through which air can escape, the instantaneous blast of air into the tire exceeds the rate of air escape, the tire is partially inflated and the seal is achieved.
A problem with the air ring is that it requires operation of both the conventional air line and air ring to initiate the seal and different types of rings are required for different sizes of tires.
A problem with the portable tank is that the tank is awkward to handle, a single tire can be inflated with the determined volume of air supply in the tank, and the release of such an air blast as necessary to achieve sealing can be dangerous. The tank requires rapid opening of a crank-type valve but holding onto the valve is important for controlling the direction of the air blast. Should the operator have any mishap such as his hand slipping off of the valve, the tool may unintentionally be whipped about by the air blast and cause injury or damage.